The invention relates generally to an implant system for the stabilization of the spine, and more particularly to a transverse connector, which is conveniently adjustable for connection of two lateral stabilizer members, i.e. spinal rods, which span the length of multiple vertebrae.
The field of orthopedics has grown in its development of spinal stabilization systems, which can be surgically implanted in order to remedy a number of medical indications, such as for example, spinal curvatures and fixation for stability in fusion procedures. Implant design must include considerations of the obfuscation within the biological environment, and the stress of in-situ surgical assembly. Spinal surgeons work with a very limited space with great concern as to minimizing the amount of time that the procedure takes, and avoiding undue disruption to the surrounding tissues. While the components of the system are small, it is important that they are as easy to assemble as possible and that they are not cumbersome.
Typically, spinal stabilization systems comprise an elongated stabilizer which can be a cable or plate member, but most often comprises a rod. The rod is held in position, usually on the posterior side of at least two vertebrae alongside the spinous process, by anchoring members which have a component that secures or clamps the rod into a fixed position longitudinally, and a component that secures the anchor in place relative to the vertebral body, i.e. a hook or screw. Of course, the anchor can be an integral unit with the screw or hook securing member. Thus with respect to the present invention, a first assembly includes a stabilizer rod or plate, and multiple anchoring members. Typically a spinal construct will include two such assemblies, one on each lateral side of the spinous processes. In order to impart further stability to the construct, it typically also includes laterally extending members which connect the two stabilizers. These connecting members are often termed xe2x80x9ctransverse connectorsxe2x80x9d.
The present invention relates to a transverse connector design, which has an adjustable length to its longitudinal linking portion. This linking area constitutes a linking assembly which joins the clamping or locking members which clamp or lock the transverse connector to the stabilizers. The present invention could include various clamping or locking means such as a rod or plate receiving recess and biasing member, which is preferably a setscrew, or vise arms or other means which form an interlocking engagement between the clamping or locking member, and rod or plate stabilizer.
The linking assembly includes two members. One is a first receiving member which has a recess to receive an extension of the second member. This structure forms a telescoping relationship between the first and the second parts of the transverse connector. A setscrew or the like can be used to lock the parts into a desired relative position when it has been achieved. The first or receiving member also has a sliding keyway which enables the parts to be disengaged or engaged but which further provides a means for limiting the amount of extension between the parts so as to inhibit the disengagement of the linking assembly through over-extension. Further the assembly allows for adjustment so that the relative positions of the two parts can be adjusted both with respect to the distance between them, (i.e., the relative longitudinal length) as well as with regard to the relative angle about the longitudinal axis of the two end clamping portions. Thus, the engagement is maintained but the clamping members can be adjusted in and out and rotated to suit the relative position of the rods. Further, the assembly can be disengaged in order to permit assembly with a second linking member having a variety of lengths in the extension.
The object of the invention is to provide a transverse connector which can provide for an adjustable length between two clamping members. The transverse connector has a two part telescoping linking portion including a vertical slot, or keyway, which allows the parts to be easily engaged prior to or during surgery but which limits the members from being inadvertently disassembled during implantation. Thus, in the event that a greater length needs to be spanned, linking part with a longer connector can be selected on the spot. Also, the relative angles of the clamp can be adjusted to account for deviations in the rods (such as might occur if the rods are bent as part of the procedure.)